The baculovirus expression system was used for the synthesis of dengue viral proteins from cloned DNA sequences. A stable recombinant baculovirus containing the Bg1 II cleaved DNA fragment coding for the three structural proteins (capsid (C), matrix (M) and envelope (E)) and nonstructural proteins NS1 and NS2A was constructed. Recombinant virus infected insect sf9 cells exhibited positive immunofluorescence staining with antibodies specific for dengue E, Pre M (the precursor of M) or NS1 glycoprotein. This indicates that the dengue DNA sequence was transcribed and the resulting mRNA was properly translated in insect cells to produce these dengue glycoprotein products. Analysis of proteins produced in baculovirus recombinant infected cells by SDS-polyacrylamide gel electrophoresis followed by "western" blotting identified E and NS1 (and probably Pre M) similar in size to authentic proteins produced during dengue virus infection. These observations suggested that proteolytic cleavage and glycosylation of these dengue proteins was normal in the baculovirus expression system. Immunization of rabbits with lysates from baculovirus recombinant infected sf9 cells induced antibodies specific to each of the three dengue glycoproteins as indicated by radio-immune precipitation a protection study in mice is currently in progress to determine whether immunized animals are resistant to challenge by dengue virus.